Abstract
The growing demands of satellite sensing and non-terrestrial networks call for efficient onboard processing,
low-latency inference, and reduced dependence on resource-intensive digital computation. Conventional
satellite remote-sensing systems typically follow a “digitize-then-process” paradigm, where
high-dimensional sensing data are digitally processed onboard or transmitted to terrestrial stations for
subsequent reconstruction and semantic inference, resulting in substantial computational and communication
overhead.
This talk explores an alternative “compute-while-transmitting” paradigm that exploits
electromagnetic wave propagation as a physical computational process. As a representative case study, we
present a stacked intelligent metasurface-based diffractive neural network for onboard terrain
classification directly from Synthetic Aperture Radar (SAR) Level-0 raw data. Multiple programmable
metasurface layers are jointly optimized to perform task-oriented feature mapping in the wave domain, while
received signal intensities at the terrestrial station directly provide semantic classification outputs. A
lightweight phase-domain augmentation strategy is further introduced to improve the learnability of
complex-valued raw SAR signals under speckle, Doppler distortions, and other impairments.
Numerical results demonstrate approximately 90% classification accuracy for binary terrain recognition
directly from real SAR Level-0 data, while reducing reliance on conventional digital processing and
high-dimensional raw-data transmission. More complex multi-class experiments further reveal the
representational limitations of purely linear in-wave processing, motivating nonlinear and hybrid physical
computing mechanisms.
Beyond SAR classification, this work highlights the potential of programmable electromagnetic structures to
evolve from communication components into task-oriented physical computing platforms, opening opportunities
for integrated sensing, communication, and computation in future terrestrial and non-terrestrial network
architectures.
Biography
Mengbing Liu received the B.E. degree in Electronic Information Engineering from Northeastern University,
China, in 2018, and the M.E. degree in Electronics and Communications Engineering from the University of
Science and Technology of China, China, in 2021. She is currently pursuing the Ph.D. degree with the School
of Electrical and Electronic Engineering, Nanyang Technological University, Singapore.
Her research focuses on physics-driven machine learning and intelligent wireless systems, with particular
interests in stacked intelligent metasurfaces, reconfigurable intelligent surfaces, in-wave and analog
computing, and integrated communication, sensing, and computation. Her recent work explores programmable
electromagnetic structures for physical-layer inference and task-oriented processing in next-generation
wireless and satellite systems. Her research has appeared in leading venues including IEEE TWC, IEEE TCCN,
and IEEE Wireless Communications, among others.